Quantum optics

The quantum nature of light gives rise to many counter-intuitive phenomena not achievable in classical optics. These have been already demonstrated to enable or enhance applications in several fields. Most notably, quantum optics can be the basis for secure communications schemes, much faster computational algorithms, and improved measurement modalities. It is widely expected, that these developments will have a significant impact on future technologies and high-technology industry.

To fulfill the potential of quantum optics, it will be necessary to integrate all the needed functionalities using state-of-the-art photonic technology. This will on one hand enhance the stability and applicability of established quantum optical techniques, on the other hand it will allow for new applications not achievable with conventional optics.

Dispersion engineered
photonic crystal waveguide.

Our research is focused on the integration of quantum optics and the exploration of new possibilities arising from such integration. To this end we make use of advanced concepts from integrated optics, nano optics, and nonlinear optics. Specifically, we are striving to develop novel sources for entangled pairs of photons based on the nonlinear effect of spontaneous parametric down-conversion, where an incident pump photon is split into two correlated photons. Using e.g. the coupling between several spatial modes in waveguide systems, the dispersion control offered by periodic structuring, or localized resonances in nanoantennas, we are aiming to control all relevant degrees of freedom of the generated two-photon quantum state, e.g. its spatial distribution, spectrum, and polarization.

Building on such tailored sources for photon pairs we are furthermore developing new approaches for quantum enhanced measurement techniques based on correlated photons. These open up the possibility for enhanced sensitivity and spatial resolution compared to classical techniques. Additionally, correlated photon pairs with photons of different wavelength enable measurements in spectral ranges for which no detectors are available by detecting only one of the photons in an accessible spectral range and deducing the information about the other photon from these measurements.